(-5,-7) you always have to start with the x axis which will give you the x coordinate. The y axis gives you -7 the x gives -5. (x,y)
It is a rational number because 98.45 can be turned into a fraction.
Each of A, C, and D are rational, so presumably B is the answer here.
A is rational, since
![10\times0.3=3](https://tex.z-dn.net/?f=10%5Ctimes0.3%3D3)
, so
![0.3=\dfrac3{10}](https://tex.z-dn.net/?f=0.3%3D%5Cdfrac3%7B10%7D)
.
C is also rational. If
![x=0.777\ldots](https://tex.z-dn.net/?f=x%3D0.777%5Cldots)
, then
![10x=7.777\ldots](https://tex.z-dn.net/?f=10x%3D7.777%5Cldots)
. This would mean
![10x-x=9x=7](https://tex.z-dn.net/?f=10x-x%3D9x%3D7)
, and so
![x=\dfrac79](https://tex.z-dn.net/?f=x%3D%5Cdfrac79)
.
D is rational by a similar argument. If
![x=0.4545\ldots](https://tex.z-dn.net/?f=x%3D0.4545%5Cldots)
, then
![100x=45.4545\ldots](https://tex.z-dn.net/?f=100x%3D45.4545%5Cldots)
. So,
![100x-x=99x=45](https://tex.z-dn.net/?f=100x-x%3D99x%3D45)
, which means
![x=\dfrac{45}{99}=\dfrac5{11}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B45%7D%7B99%7D%3D%5Cdfrac5%7B11%7D)
.